.box {
  overflow: hidden; }

.box > div {
  float: left; }

.num1 {
  border-top: 20px solid red;
  border-right: 20px solid transparent;
  border-bottom: 20px solid transparent;
  border-left: 20px solid transparent; }

.num2 {
  border-top: 30px solid transparent;
  border-right: 30px solid transparent;
  border-bottom: 30px solid pink;
  border-left: 30px solid transparent; }

.num3 {
  border-top: 40px solid transparent;
  border-right: 40px solid transparent;
  border-bottom: 40px solid transparent;
  border-left: 40px solid blue; }

.num4 {
  border-top: 50px solid transparent;
  border-right: 50px solid yellow;
  border-bottom: 50px solid transparent;
  border-left: 50px solid transparent; }
